How to install the hydraulic hoses properly?

The installation and piping of hoses is not as simple as tightening the joints. The life of a hose is not eternal, but learning some basic piping principles before installation helps to maximize its service life.

First, appropriate hose length

Metal hose has a longer service life than ordinary hose, but it is not flexible.

If you need a pressure resistant flexible pipe, a hose is your best choice. Hydraulic hose is used to transfer pressure fluid in the moving state. When the hose is connected straight, its length must be greater than the distance from the port to the port. Because when the hose is under pressure, under pressure, the diameter will increase, and the length will decrease.

Under pressure, the length can be reduced by up to 4%. This means that a 1 meter long hose will be shortened by 4cm!

Therefore, if there is not enough slack, the hose joint joint will be subjected to excessive pressure and cause leakage or worse. The hose can be pulled loose from the joint, causing a catastrophic failure. It is important to maintain adequate slack, but too much slack may risk wear on the hose assembly or human tripping.

Second, the appropriate bending radius

A hydraulic hose is flexible, but its steel wire reinforcement also gives it associated mechanical properties that limit its flexibility. One of the limitations is the minimum bend radius of the hose, that is, how far you can bend the hose from the arc to the sharp corner before the wire reinforcement begins to twist.

Think of it this way: Hold each end of a piece of hose in each hand and press it firmly into a "U" shape. The distance between the two ends is the bending diameter, half of which is the bending radius. Some hoses have a smaller bend radius than others and are therefore more flexible.

Another important principle when installing a hose assembly is the need to consider where the hose meets the hose connector. If the hose needs to be bent immediately near the metal joint position, the principle should be observed: it needs to start bending at least 2 times the diameter of the pipe. Therefore, if the outer diameter of the hose is 15mm, the length from the bend to the hose joint should not be less than 30mm. If this is not possible, consider using a 90° or 45° hose connector.

When the pressurized fluid enters the hose at high speed, you do not want it to "impact" the inner tube, because over time, this will rapidly degrade the inner core and greatly shorten the service life of the hose. If you "maintain a straight length twice the outer diameter", you should be able to allow fluid to flow unimpeded into the hose, minimizing the risk of premature core failure.

Third, avoid hose distortion

A hydraulic hose is flexible, but its steel wire reinforcement also gives it associated mechanical properties that limit its flexibility. One way to reduce mechanical stress is to avoid hose distortion. Marking can be used to determine whether the hose is twisted when distributing the pipe. If the mark looks squiggly, the hose is twisted during installation. After the two ends should be loosened to eliminate the distortion, use two wrench methods, one wrench to secure the hose to prevent distortion and the other wrench to tighten the joint.

The next piping principle is still aimed at preventing hose distortion. Simply put, you need to limit the bending of the hose to a single dimensional "plane." Think of it this way: the hose moving from left to right is moving in a plane or dimension, as is the hose moving only up and down or back and forth. Any combination of left/right, front/back, up/down motion represents 2-dimensional plane motion, while the combination of all three represents 3-dimensional plane motion. Multiple plane movements are called "composite bending," which can cause the hose to twist because the hose ends are already secured. Therefore, the principle of pipe distribution requires that the hose can only move in one plane at most; However, if your application requires flexible multiplane motion, ask a ParkerStore expert for advice.

Fourth, tube distribution and fixing

One of the main causes of premature hose breakage is wear, which causes the outer rubber layer to disappear, and when the wire reinforcement layer is exposed to moisture, it begins to rust and deteriorate, thereby reducing the service life of the hose.

For this purpose, the piping principle requires that the hose be clamped and fixed in the appropriate position to prevent wear. In Part 1 of the Piping Principles, we talked about how hoses shorten under pressure, so don't over-clamp the hose! Friction between hoses can also cause wear, so each hose should be clamped separately.

5. Plan ahead

Have you ever had to remove a lot of obstacles or buy a special tool to get the wrench over the nut in order to unscrew a hose joint? Proper piping planning for future maintenance can help save time. For example, on a hydraulic valve block, there are multiple hoses stacked on top of each other in a very small space. In order to reach the hose connector, you need to remove the hose located at the front end. Also, don't forget which hose is connected to which port! Using a combination of hose joints and hard pipe joints can effectively avoid this situation. We have long and short direct head and bend joint to choose from, so that when the pipe is distributed, it can be more beautiful and convenient. This one example alone shows that the right type of piping can make future maintenance easier and reduce downtime.

Six, review the principles of distribution

Let's review the basic piping principles:

Under pressure, the hose will shrink up to 4%, so adequate relaxation should be maintained. The bending radius of the hose must not be less than its minimum bending radius. When one end of the hose is fixed, the length from the joint to the bend should not be less than 2 times the inner diameter of the hose. During the installation, use the "double wrench" mode and observe the label to check whether the hose is distorted. Limit the bend of the hose to a flat surface. Clamp hose to prevent wear. Keep hose piping clean for future maintenance.

By following these simple principles, it helps to maximize the service life of your hydraulic hose.